[FFmpeg-devel] [PATCH v4 2/5 v2] lavf/movenc: Add support for palette side data

Mats Peterson matsp888 at yahoo.com
Wed Mar 2 23:19:58 CET 2016


On 03/02/2016 11:07 PM, Mats Peterson wrote:
> On 03/02/2016 10:30 PM, Michael Niedermayer wrote:
>>> +                ret = 0;
>>> +            if (trk->enc->pix_fmt == AV_PIX_FMT_PAL8 &&
>>> !trk->pal_done) {
>>> +                const uint8_t *pal;
>>> +                int ret2 = ff_get_packet_palette(s, opkt, ret, &pal);
>>> +                if (ret2 < 0)
>>> +                    return ret2;
>>> +                if (pal) {
>>> +                    memcpy(trk->palette, pal, AVPALETTE_SIZE);
>>
>> this fails on big endian
>> AV_PKT_DATA_PALETTE is stored in cpu endianness
>>
>> in general AVPacket->data is defined byte per byte and can be stored
>> as is byte per byte
>> AVPacket->side_data is in whatever endianness
>> people preferred at the time a specific AV_PKT_DATA_* was added.
>> in case of AV_PKT_DATA_PALETTE its native cpu endianness
>>
>
> Messy! But alright, thanks for the info.
>

I just don't understand why the palette when stored in AVPacket->data is 
in little-endian format when it is stored byte by byte. And I can't find 
the place where this is done. It would be more logical to use big-endian 
format.

Mats



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